A bromine-containing flame retardant and its preparation method and application

Abstract

The present invention relates to the field of flame retardant technology, in particular to the field of IPC C08L, and more specifically to a bromine-containing flame retardant and a preparation method and application thereof. The present invention prepares a bromine-containing flame retardant through a Grignard reaction, and the flame retardant alone has excellent flame retardant effect, especially a bromine-containing flame retardant with a double bond at the end, and the bromine-containing flame retardant is mixed with specific polystyrene, an initiator, a stabilizer and other raw materials to prepare a bromine-containing flame retardant polystyrene foam material, which has excellent flame retardant effect and is safe and environmentally friendly.

Description

Technical Field

[0001] The present invention relates to the field of flame retardant technology, in particular to the field of IPC C08L, and more specifically to a bromine-containing flame retardant and a preparation method and application thereof. Background Art

[0002] Polystyrene foam materials have the advantages of good mechanical properties, low price, simple and easy to implement molding equipment, excellent thermal insulation performance and simple construction operation. They have been widely used in building insulation fields such as building exterior insulation, roof insulation, interior insulation, and sandwich insulation. Polystyrene foam materials can be divided into extruded polystyrene foam materials (XPS) and expandable polystyrene foam materials (EPS). However, the limiting oxygen index of polystyrene foam is only about 20%, which is a flammable material. In addition, a large amount of toxic gas and thick smoke will be produced during its combustion, and there will be molten dripping, which can easily cause fire spread and secondary injuries. In recent years, many fires in building exterior insulation, such as the Glanfield Building fire in London, UK in 2017 and the Zhongxin Building fire in Shijiazhuang, Hebei in 2021, were caused by the ignition of the polystyrene foam insulation material on the exterior wall and the spread of fire. Therefore, polystyrene foam materials for building insulation must be flame retardant modified.

[0003] Hexabromocyclododecane (HBCD) has been widely used in polystyrene foam materials as a highly effective flame retardant, but it will migrate into the environment during use, posing potential long-term hazards to humans and the environment. With the implementation of my country's "Amendment to the Stockholm Convention on Persistent Organic Pollutants to Add Hexabromocyclododecane", HBCD was officially banned on December 26, 2021. With the promulgation of the ban, the replacement of HBCD and the development of high-efficiency flame retardants for polystyrene have become research hotspots in the field of flame retardancy. People have successively studied the effects of various flame retardants such as bromine-containing flame retardants, intumescent flame retardants, expandable graphite, phosphorus-nitrogen-silicon (boron) on the performance of polystyrene foam materials, and developed a variety of flame retardant methods such as blended flame retardant, copolymer flame retardant and coating / coating flame retardant. Bromine-containing flame retardants are still the most effective in retardant polystyrene foam materials, such as methyl octabromoether and decabromodiphenylethane. However, these flame retardants are small molecule flame retardants with poor thermal stability and compatibility with polystyrene. During long-term use, they are as easy to migrate from polystyrene foam materials to the external environment as HBCD, which will not only pollute the environment but also cause the attenuation of the flame retardant properties of polystyrene foam materials.

[0004] The patent document with application number CN 202111482089.6 discloses a reactive flame retardant modified polystyrene foam material and a preparation method. Starch-based melamine phytate is used as a reactive expansion flame retardant and grafted into the polystyrene foam matrix, which reduces the effect of the flame retardant on the mechanical strength of the foam material and gives the material excellent flame retardancy and smoke suppression. However, its flame retardancy is weak and the limiting oxygen index is low.

[0005] The patent document with application number CN 202110031101.5 discloses a composite bromine-based flame retardant with high thermal stability and its high-efficiency flame-retardant polystyrene foam material. The composite flame retardant containing a thermal stabilization system, a hydrobromic acid absorber and an antioxidant can achieve thermal stability of the flame retardant during the processing of polystyrene foam materials, but its flame retardancy is relatively weak and its limiting oxygen index is low.

[0006] Therefore, how to improve the thermal stability of bromine-containing small molecule flame retardants, their compatibility with polystyrene materials, and improve their flame retardant efficiency has become a technical problem that needs to be solved urgently. Summary of the invention

[0007] In order to solve the above problems, the present invention provides a bromine-containing flame retardant in the first aspect, whose structural formula is Where R is CH2=CH(CH2) n -、CH3CH2(CH2) m - any one; n = 0 ~ 3, m = 0 ~ 3; wherein n and m can independently be 0, 1, 2, 3.

[0008] More preferably, the R is CH2=CH(CH2) n -, n=1.

[0009] In a second aspect of the present invention, a method for preparing the bromine-containing flame retardant is provided, the steps of which include:

[0010] S1, Grignard reaction: Add reactant I and solvent into a flask, turn on condensation reflux, and place in a -5°C ice-water bath; continue to add 3-bromopropyltrichlorosilane into a constant pressure dropping funnel, and dropwise add into the flask within 1 to 2 hours, maintaining the temperature of the reaction system at -5 to 10°C. After the dropwise addition is complete, continue the reaction for 3 to 6 hours to obtain solution 1;

[0011] S2, Grignard reagent quenching reaction: Take the quenching agent and add it to the constant pressure dropping funnel, add it dropwise to solution 1 within 1 to 2 hours, and continue the reaction for 1 to 2 hours to obtain solution 2;

[0012] S3, layered distillation: layer solution 2, take the upper clear liquid, and distill at 100-150° C. and -0.06--0.098 MPa to obtain the final bromine-containing flame retardant.

[0013] The preparation process needs to be in an anhydrous and oxygen-free environment.

[0014] Preferably, the structural formula of the reactant I is R-Mg-Br; wherein R is CH2=CH(CH2) n -、CH3CH2(CH2) m - one of; n = 0 ~ 3, m = 0 ~ 3; further preferably, the R is CH2 = CH (CH2) n -, n=1.

[0015] Preferably, the weight ratio of the reactant I to 3-bromopropyltrichlorosilane is 1:(2-5).

[0016] Preferably, the solvent includes but is not limited to one or more of diethyl ether, N,N-dimethylformamide, and acetonitrile.

[0017] Preferably, the amount of the solvent added is 20-60 wt % of the raw material in step S1.

[0018] The reaction equation of reaction S1 is as follows:

[0019]

[0020] Preferably, the quencher includes but is not limited to one or more of sodium chloride and magnesium chloride.

[0021] Preferably, the amount of the quencher added is 40-60wt% of the total raw materials in step S1.

[0022] The inventor creatively discovered that by selecting reactant I as a Grignard reagent and carrying out a Grignard reaction with 3-bromopropyltrichlorosilane under specific conditions, the final bromine-containing flame retardant can be smoothly prepared while avoiding the occurrence of side reactions, thereby affecting its flame retardant effect. This may be due to the excellent flame retardant properties of the three-crosslinked silicon-containing chain bromine-containing flame retardant, and in the process of preparing the bromine-containing flame retardant, the coupling between the reactants is avoided by dripping and controlling the temperature of the reaction system, and the anhydrous and oxygen-free conditions are strictly controlled to avoid the Grignard reagent and water or oxygen from reacting to form alkanes or alkoxides.

[0023] The third aspect of the present invention provides the application of the bromine-containing flame retardant, which is used for preparing bromine-containing flame retardant polystyrene foam material. The raw materials for preparing the bromine-containing flame retardant polystyrene foam material include, by weight: 70-90 parts of polystyrene, 5-30 parts of bromine-containing flame retardant, 0.5-5 parts of initiator, and 0.3-4 parts of heat stabilizer.

[0024] Preferably, the weight average molecular weight (Mw) of the polystyrene is 2000-2800 g / mol, and the number average molecular weight (Mn) is 1800-2500 g / mol; further preferably, the weight average molecular weight (Mw) of the polystyrene is 2400 g / mol, and the number average molecular weight (Mn) is 2200 g / mol.

[0025] In some preferred embodiments, the polystyrene is purchased from MacLean Reagent, with CAS No. 9003-53-6 and serial No. P816874.

[0026] Preferably, the initiator is at least one of azobisisobutyronitrile, sodium pyrosulfite and potassium persulfate.

[0027] Preferably, the stabilizer is at least one of tribasic lead sulfate, organic tin and organic antimony.

[0028] The inventor creatively discovered that the introduction of a double bond at the end of the bromine-based flame retardant prepared in the present application can improve the flame retardant effect of the bromine-containing flame-retardant polystyrene foam material, and the product is safer and more environmentally friendly. This may be due to the good copolymerization effect of the bromine-based flame retardant with a double bond at the end and the styrene monomer in the present application, which can be chained to the polystyrene molecular chain, thereby reducing the migration of small molecule flame retardants, improving the flame retardant effect of the prepared bromine-containing flame-retardant polystyrene foam material, and the apparent density is small, the material distribution is more uniform, and the precipitated toxic bromine-containing compounds are reduced, which helps to improve the safety and environmental performance of the product.

[0029] The preparation method of the flame-retardant polystyrene foam material is as follows: the polystyrene, bromine-containing flame retardant, initiator and heat stabilizer are added into a twin-screw extruder to form a molten state at a high temperature of 200 to 250° C., and then cooled at 50 to 90° C. through a discharge port to form a polymer stream, and then cut to form flame-retardant polystyrene foam materials of different shapes and specifications.

[0030] Beneficial effects:

[0031] 1. The present invention selects reactant I as a Grignard reagent and performs a Grignard reaction with 3-bromopropyltrichlorosilane under specific conditions, thereby being able to smoothly prepare the final bromine-containing flame retardant while avoiding the occurrence of side reactions that affect its flame retardant effect.

[0032] 2. The introduction of a double bond at the end of the bromine-based flame retardant prepared in the present application can improve the flame retardant effect of the bromine-containing flame retardant polystyrene foam material, and the product is safer and more environmentally friendly.

[0033] 3. The present invention prepares a bromine-containing flame retardant through the Grignard reaction. The flame retardant alone has excellent flame retardant effect, especially the bromine-containing flame retardant with a double bond at the end. The bromine-containing flame retardant is mixed with specific polystyrene, initiator, stabilizer and other raw materials to prepare a bromine-containing flame retardant polystyrene foam material. The material has excellent flame retardant effect and is safe and environmentally friendly. DETAILED DESCRIPTION

[0034] Example

[0035] All raw materials in the examples are measured by weight.

[0036] Example 1

[0037] Example 1 provides a bromine-containing flame retardant having the structural formula Where R is CH2=CH(CH2) n -; n=1.

[0038] The preparation method comprises the following steps by weight:

[0039] S1, Grignard reaction: Under anhydrous conditions, prepare a reaction flask, overhead stirring, a constant pressure titration funnel, condensation reflux and an ice-water bath environment (set an ice bath at -5°C); after installing the device, add 30 parts of reactant I and 60 parts of solvent to the flask, turn on condensation reflux and ice-water bath; continue to add 10 parts of 3-bromopropyltrichlorosilane to the constant pressure dropping funnel, dropwise add to the flask within 1 hour, maintain the temperature of the reaction system at 5°C, and continue the reaction for 5 hours to obtain solution 1;

[0040] S2, Grignard reagent quenching reaction: Take 50 parts of quenching agent and add it to the constant pressure dropping funnel, add it dropwise to solution 1 within 2 hours, and continue the reaction for 2 hours to obtain solution 2;

[0041] S3, layered distillation: layer solution 2, take the upper clear liquid, and distill at 120°C, -0.098Mpa to obtain the final bromine-containing flame retardant product.

[0042] The structural formula of the reactant I is R-Mg-Br; wherein R is CH2=CH(CH2) n -; n=1.

[0043] The solvent is N,N-dimethylformamide.

[0044] The bromine-containing flame retardant is:

[0045] Example 2

[0046] Example 2 provides a bromine-containing flame retardant, and the specific implementation method is the same as that of Example 1, except that: wherein R is CH2=CH(CH2) n -; n=0.

[0047] The structural formula of the reactant I is R-Mg-Br; wherein R is CH2=CH(CH2) n -; n=0.

[0048] The bromine-containing flame retardant is:

[0049] Example 3

[0050] Example 3 provides a bromine-containing flame retardant, and the specific implementation method is the same as that of Example 1, except that: R is CH2=CH(CH2)n-; n=2.

[0051] The structural formula of the reactant I is R-Mg-Br; wherein R is CH2=CH(CH2) n -; n=2.

[0052] The bromine-containing flame retardant is:

[0053] Example 4

[0054] Example 4 provides a bromine-containing flame retardant, and the specific implementation method is the same as that of Example 1, except that: wherein R is CH3CH2(CH2) m -, m=1.

[0055] The structural formula of the reactant I is R-Mg-Br; wherein R is CH3CH2(CH2) m -, m=1.

[0056] The bromine-containing flame retardant is:

[0057] Example 5

[0058] Example 5 provides a bromine-containing flame retardant, and the specific implementation method is the same as that of Example 1, except that: wherein R is CH3CH2(CH2) m -, m=0.

[0059] The structural formula of the reactant I is R-Mg-Br; wherein R is CH3CH2(CH2) m -, m=0.

[0060] The bromine-containing flame retardant is:

[0061] Example 6

[0062] Example 6 provides a bromine-containing flame retardant, and the specific implementation method is the same as that of Example 1, except that: wherein R is CH3CH2(CH2) m -, m=2.

[0063] The structural formula of the reactant I is R-Mg-Br; wherein R is CH3CH2(CH2) m -, m=2.

[0064] The bromine-containing flame retardant is:

[0065] Example 7

[0066] Example 7 provides a flame retardant polystyrene foam material, and its preparation raw materials include, by weight: 15 parts of the bromine-containing flame retardant prepared in Example 1, 80 parts of polystyrene, 3 parts of initiator, and 2 parts of stabilizer.

[0067] The weight average molecular weight (Mw) of the polystyrene is 2400 g / mol, and the number average molecular weight (Mn) is 2200 g / mol.

[0068] The polystyrene was purchased from MacLean Reagent, with CAS No. 9003-53-6 and serial No. P816874.

[0069] The initiator is azobisisobutyronitrile.

[0070] The stabilizer is tribasic lead sulfate.

[0071] The preparation method of the flame-retardant polystyrene foam material comprises the following steps: adding the above-mentioned polystyrene, bromine-containing flame retardant, initiator and heat stabilizer into a twin-screw extruder to form a molten state at 230° C., then cooling through a discharge port at 70° C. to form a polymer stream, and cutting to form flame-retardant polystyrene foam materials of different shapes and specifications.

[0072] Example 8

[0073] Example 8 provides a flame retardant polystyrene foam material, and the specific implementation method is the same as that of Example 7, except that: in parts by weight, the raw materials for its preparation include: 15 parts of the bromine-containing flame retardant prepared in Example 4, 80 parts of polystyrene, 3 parts of initiator, and 2 parts of stabilizer.

[0074] 1. Performance test of brominated flame retardants

[0075] Test method of limiting oxygen index: The phosphorus-containing flame retardants prepared in Examples 1-4 and Comparative Example 1 were tested according to the method in GB / T 2406.2-2009, and the addition amount of the flame retardant was 6%. The oxygen index was greater than 27%, which was a flame retardant material, and the larger the oxygen index, the better the flame retardant performance. The UL-94 grade was graded according to the limiting oxygen index, greater than or equal to 33.0 was V-0, 31.0 to 33.0 was V-1, 27.0 to 31.0 was V-2, and less than or equal to 27.0 was NR. The results were recorded in Table 1.

[0076] Table 1

[0077] Limiting oxygen index / % UL-94 Rating Example 1 34.8 V-0 Example 2 33.1 V-0 Example 3 33.7 V-0 Example 4 31.4 V-0 Example 5 31.2 V-0 Example 6 33.0 V-0

[0078] It can be seen from Table 1 that when the terminal group is an olefin bond, the flame retardant effect is best when n=1; when the terminal group is an alkyl group, the flame retardant effect is best when m=2, indicating that the flame retardant performance of the three-crosslinked silicon-containing chain bromine-containing flame retardant is better.

[0079] 2. Performance test of flame retardant polyester foam material

[0080] The limiting oxygen index and UL-94 rating are the same as above.

[0081] Test method for apparent density: Use an analytical balance to test the apparent density of the foamed product according to standard GB1033-86. The results are recorded in Table 2.

[0082] Table 2

[0083]

[0084] As can be seen from Table 2, after grafting with polystyrene materials, the flame retardant ability of the original bromine-containing flame retardant has decreased. However, the UL-94 grade of the product of Example 4 with an olefin bond as the terminal group is still V-0, indicating that the olefin bond as the terminal group can significantly improve the compatibility of the bromine-containing flame retardant with polystyrene foam materials and reduce the migration of small molecule flame retardants. In particular, the three-crosslinked olefin bond makes it have the best flame retardant performance when the branch chain carbon atoms are 3. In addition, the apparent density is small and the material distribution is relatively uniform.

Claims

1. An application of a bromine-containing flame retardant, characterized in that: The invention is used for preparing a bromine-containing flame-retardant polystyrene foam material. The raw materials for preparing the bromine-containing flame-retardant polystyrene foam material include, by weight: 70-90 parts of polystyrene, 5-30 parts of a bromine-containing flame retardant, 0.5-5 parts of an initiator, and 0.3-4 parts of a heat stabilizer; The structural formula of the bromine-containing flame retardant is , where R is CH2=CH(CH2) n -、CH3CH2(CH2) m - any one; n = 0 ~ 3, m = 0 ~ 3; wherein n and m can independently be 0, 1, 2, 3.

2. The use of the bromine-containing flame retardant according to claim 1, characterized in that: The weight average molecular weight of the polystyrene is 2000-2800 g / mol, and the number average molecular weight is 800-2500 g / mol.

3. The use of the bromine-containing flame retardant according to claim 1, characterized in that: The initiator is at least one of azobisisobutyronitrile, sodium pyrosulfite and potassium persulfate.

4. The use of the bromine-containing flame retardant according to any one of claims 1 to 3, characterized in that: The stabilizer is at least one of tribasic lead sulfate, organic tin and organic antimony.

Images